Time-series plots from two muon telescopes at Georgia State University

Our measurement of cosmic ray muon flux variation at Georgia State University continues. The plots below are from two independent muon telescopes located in different buildings.

Two-paddle muon telescope (15cmx15cm paddle; 2″ apart)


Two-paddle muon telescope


Both detectors saw the flux rising trend during the last week of October, 2017. It was very windy and cold in the Atlanta area on October 29, 2017. The monthly pressure and temperature of October 2017 in Atlanta is here. One sees the typical anti-correlation between the cosmic ray muon flux and the atmospheric pressure.



Multiple Car Fires on the Roads in Atlanta on March 29, 2017

There were at least three car fires on the roads in Atlanta reported from the traffic news on NPR, March 29, 2017. I am wondering if there is any potential correlation between these events and the solar activity.

Over the past a few years, I have been paying close attention to any report like this given my own research interests of studying the cosmic ray radiation and the associated applications.

A quick googling reveals the article published in Advances in Space Research,

On statistical relationship of solar, geomagnetic and human activities

by M.V. Alania et al.  The link to this paper is here:  http://www.sciencedirect.com/science/article/pii/S0273117704003357

New News on Cancer Causes

A new article in “Science” (Tomasetti et al., Science 355, 1330-1334 (2017)) is interesting to read. It is highlighted in the Science News today, as shown below:

Screen Shot 2017-03-24 at 8.28.09 AM

I tend to agree with the authors’ claim and think that it could be largely connected to the intensive high energy cosmic ray showers that reach to the surface of the earth.

Cosmic Ray Shower Simulation

While we are building cosmic ray detectors, there is also a Monte Carlo simulation program we developed at GSU for studying the interactions between the primary cosmic ray particles (primarily protons) and the atmospheric molecules. This software is based on the Geant4 package developed at CERN (http://geant4.cern.ch/) which has been used extensively in the field of high energy nuclear and particle physics, medical physics and space science.

I am posting here two sets of screen images of the simulated event displays from one 100-GeV and one 10-TeV proton shower. Could you imagine what will happen to a person who happens to be situated within the vicinity of the showers.

100gev 10tev

Correlations between the cosmic ray muon flux variations and the atmosphere pressure change

The correlations between the cosmic ray muon flux variation measured at the surface of the earth and the atmospheric pressure has been known for more than half a century [Nature 183, 451-452 (14 February 1959); doi:10.1038/18345a0, etc].

In this blog, I would like to show two screen shots of the muon flux variations measured from two portable muon telescopes at Georgia State University (GSU), in downtown Atlanta. One of these two detectors (SA402) is installed in my office for the time being as I pointed out in my previous blogs, which has been recording data since the mid September of 2016, as shown below:


The other detector is installed in a different building on the GSU campus and has been recording data since the mid January of 2017. The month-worth of data is seen as follows:


The distinct peaks (i.e., higher muon counts) are clearly seen in these plots around Jan 23, Feb 9 and 15. The following weather plots were taken from the Weather Underground [https://www.wunderground.com/history/airport/KFTY/2017/1/15/CustomHistory.html?dayend=15&monthend=2&yearend=2017&req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=]. One can quickly spot the low pressure days from Jan 15 to Feb 16, 2017 in the middle panel.


I could not wait to have our detectors installed in every corner of the globe and use the measured cosmic ray flux variations to study the dynamical changes of the weather system in real-time.

If one is interested in learning more about this topics, please check out this paper we wrote a couple of years ago on cosmic ray flux variations

“CLOUD experiment sharpens climate predictions”

I am trying to catch up my reference studies. While flipping the pages of the newest issue of “CERN COURIER” (available online at http://cerncourier.com/cws/article/cern/66876), Volume 56, Number 10, December 2016, I was attracted to one of the News – “CLOUD experiment sharpens climate predictions”.  I simply picked the title of this News article as the title of this blog post.

For those who don’t have time to read the article, “CLOUD” stands for Cosmic Leaving Outdoor Droplets, which is an experiment at CERN to understand the aerosol particles in the atmosphere and their effects on cloud.

“The new CLOUD study establishes the main processes responsible for new particle formation throughout the troposphere, which is the source of around half of all cloud seed particles”, said in this article.

“Aerosol particles form when certain trace vapors in the atmosphere cluster together, and grow via condensation to a sufficient size that they can seed cloud droplets. Higher concentration of aerosol particles make cloud more reflective and long-lived, thereby cooling the climate, and it is thought that the increased concentration of aerosols caused by air pollution since the start of the industrial period has offset a large part of the warming caused by greenhouse-gas emissions.” – also quoted from this article.

The CLOUD collaboration has published an article in Science (E.M. Dunne et al., Science, 10.1126/science.aaf2649, 2016), titled as “Global atmospheric particle formation from CERN CLOUD measurements”. It is a interesting article to read.

This reminded me a PRL paper by Henrik Svensmark, “Influence of Cosmic Rays on Earth’s Climate” [PRL 81, Number 22, 5027 (1998)], and the correlation between the Earth’s cloud coverage and the cosmic ray fluxes over the time.

New suite of cosmic ray muon detectors recently built at Georgia State University

Over the past a few months, my students and I were developing a new version of a cosmic ray muon telescope. Our goal was to build a portable and low-cost detector which could be easily duplicated and installed anywhere around the globe for studying the correlations between the cosmic ray muon flux variations and the dynamical patterns of the space and earth weather.

The following two photos show the three identical detectors we assembled. Each detector consists of three layers of scintillator tiles. The signals are read out by a Raspberry PI which is mounted at the bottom layer of the stand.



The scintillator tiles were machined at the physics machine shop at GSU. A rendering of the scintillator design is shown below:


We started taking data from two of the three detectors, called Charlie and Bravo, on January 4th, 2017. I spent a couple of hours this morning and made the following plots of the hourly muon counts recorded by Charlie and Bravo.bravo_1 charlie_1

I was very happy to see the consistent results (patterns) from these two detectors. It was even more encouraging to see the consistent trend of the muon flux variation recorded during the same time period by the two-paddle detector installed in my office. My office is located in a different building one block away from the building where Charlie and Bravo are located, as seen below,


The decreasing trend of the muon fluxes recorded by these detectors seems correlated well with the recent solar activity, http://www.spaceweather.com/archive.php?view=1&day=14&month=01&year=2017

Studying climate change is a common cause

In recent years, the climate issue has been significantly amplified by political rhetoric from all sides, though it should NOT be.  It is a common cause for all living creatures on the planet.

I have been following news on climate change over the past a few years. Unfortunately, each year has been marked as the historical high in temperature on records. The same was reported this year as it was reported from NPR news a couple of days ago while I was driving to school to work on my cosmic ray detectors.

As a physicist, I feel strongly obligated to make efforts to understand the factors which could cause the climate change using scientific tools. The measurement of cosmic ray flux variation at the global scale seems a viable method for monitoring the dynamic changes of the atmospheric and space weather.

Cosmic ray muon detector in my office (SA402, GSU)

As a baseline measurement of the cosmic ray muon flux variations in time series, I have set up a small two-paddle muon counter in my office.  The dimension of paddle is 14.5cm x 14.5cm x 1cm and the two paddles are separated by 4cm apart. A similar detector configuration is currently running in Xi’an, China at Professor Ting-Cun Wei’s research lab. The followings are the photos of this detector: the first photo shows the two-paddle detector mounted inside an extruded aluminum frame, the second shows the close-up view of the detector.  The circuit board on top of the top paddle is a Raspberry PI hat board made my my students at GSU which is mounted on a Raspberry PI.

2paddle_sa402_1 2paddle_sa402_2

There is a web server running on the PI and displaying the muon counts as a function of UTC time. A screen capture of the online display is taken this morning is shown below:





Amazingly enough, one can see a big dip of the muon counts around Dec 18, 2016 (near the end of the plot). This is a known solar modulation effect on cosmic ray flux variation.  The picture below are copied from http://spaceweather.com

alaska_strip “As predicted, Earth is entering a stream of high speed solar wind on Dec. 21st. First contact produced a surge of ground currents in Lofoton, Norway–“a good sign for very nice Northern Lights,” says Rob Stammes who measured the disturbance.  Indeed, bright auroras are now dancing around parts of the Arctic Circle. Marketa S. Murray photographed these over Fairbanks, Alaska” – quoted from the space weather website.

We are continuing our development work on building low-cost and reliable muon counts at GSU and want to build a world-wide consortia for studying cosmic ray muon flux variation at a global scale. This coordinated effort is NOT limited to research groups at institutions or universities. We also want to promote this project in middle and high schools and get young scientists started early working on collaborative research.